Cambridge International Examinations Cambridge International General Certificate of Secondary Education

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1 Cambridge International Examinations Cambridge International General Certificate of Secondary Education * * CHEMISTRY 0620/62 Paper 6 Alternative to Practical February/March hour Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. Electronic calculators may be used. You may lose marks if you do not show your working or if you do not use appropriate units. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. The syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate. This document consists of 8 printed pages. IB17 03_0620_62/6RP [Turn over

2 2 1 A student investigated the gases formed during the electrolysis of dilute sulfuric acid using the apparatus shown. Hydrogen and oxygen were produced. dilute sulfuric acid carbon... + (a) Complete the box to name the apparatus used. [1] (b) On the diagram, sketch how a sample of one of the gases could be collected. [2] (c) Give a test for oxygen. test... result... [1] (d) The gas collected at the positive side turned limewater milky. (i) Based on this observation, what gas was present? Suggest how this gas was formed. (e) A solution of dilute sulfuric acid was electrolysed for 1 hour. Suggest why the ph of the solution decreased during the electrolysis.... [2] [Total: 8]

3 3 Question 2 starts on the next page. [Turn over

4 difference / cm 3 [2] difference / cm 3 [2] 4 2 A student investigated the reaction between dilute hydrochloric acid and two different aqueous solutions of sodium hydroxide labelled solution O and solution P. Two experiments were carried out. Experiment 1 A burette was filled with dilute hydrochloric acid. The initial burette reading was recorded. Using a measuring cylinder, 20 cm 3 of solution O were poured into a conical flask. Thymolphthalein indicator was added to the conical flask. The dilute hydrochloric acid was added from the burette, while swirling the flask, until the solution just changed colour. The final burette reading was recorded. (a) Use the burette diagrams to record the readings in the table and complete the table initial reading final reading final burette reading / cm 3 initial burette reading / cm 3 Experiment 2 The conical flask was emptied and rinsed with distilled water. Experiment 1 was repeated using solution P instead of solution O. (b) Use the burette diagrams to record the readings in the table and complete the table initial reading final reading final burette reading / cm 3 initial burette reading / cm 3

5 5 (c) What type of chemical reaction occurs when dilute hydrochloric acid reacts with sodium hydroxide solution?... (d) (i) Which solution of sodium hydroxide, solution O or solution P, is the more concentrated? Explain your answer [2] How many times more concentrated is this solution of sodium hydroxide than the other solution of sodium hydroxide? (e) If Experiment 2 were repeated using 10 cm 3 of solution P, what volume of dilute hydrochloric acid would be needed?... [2] (f) What would be the effect, if any, on the volume of dilute hydrochloric acid used in Experiment 1 if the solution of sodium hydroxide were warmed before adding the dilute hydrochloric acid? Give a reason for your answer. effect on volume... reason... [2] (g) (i) What would be a more accurate method of measuring the volume of the aqueous sodium hydroxide solution? Suggest how the reliability of the results could be checked. (h) Aqueous sodium hydroxide reacts with aqueous calcium chloride to form a precipitate of calcium hydroxide. Use this information to suggest a different method of finding out which of the solutions of sodium hydroxide is the more concentrated.... [3] [Total: 17] [Turn over

6 3 Two solids, Q and R, which are both salts, were analysed. Solid Q was zinc bromide. Tests were carried out on each solid. tests on solid Q 6 Solid Q was dissolved in distilled water. The solution was divided into three equal portions in three test-tubes, and the following tests were carried out. Complete the expected observations. (a) (i) Drops of aqueous sodium hydroxide were added to the first portion of the solution until a change was seen. observations... [2] Excess aqueous sodium hydroxide was then added to the mixture. observations... [1] (b) (i) Drops of aqueous ammonia were added to the second portion of the solution until a change was seen. observations... [1] Excess aqueous ammonia was then added to the mixture. observations... [1] (c) Dilute nitric acid and aqueous silver nitrate were added to the third portion of the solution. observations... [2]

7 7 tests on solid R Tests were carried out and the following observations made. tests on solid R observations test 1 A flame test was carried out on solid R. yellow colour Solid R was dissolved in distilled water. The solution was divided into two equal portions in two test-tubes. test 2 Dilute nitric acid and aqueous barium nitrate were added to the first portion of the solution. no change test 3 Dilute nitric acid and aqueous silver nitrate were added to the second portion of the solution. yellow precipitate formed (d) Identify solid R.... [2] [Total: 9] [Turn over

8 8 4 When solid barium hydroxide is added to solid ammonium chloride a reaction takes place. (a) Describe an experiment to show that this reaction is endothermic.... [4] (b) How could you show whether or not the final mixture contains ammonium ions?... [2] [Total: 6] Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at after the live examination series. Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.

Cambridge International Examinations Cambridge International General Certificate of Secondary Education

Cambridge International Examinations Cambridge International General Certificate of Secondary Education *3090986058* CHEMISTRY 0620/61 Paper 6 Alternative to Practical May/June 2017 1 hour Candidates answer